Stroke is a common cause of death and disabling neurologic disorder. Approximately 700,000 patients suffer from stroke in the United States every year. Hemorrhagic stroke accounts for 20% of the annual stroke population. Hemorrhagic stroke is due to a rupture of a blood vessel in the brain, causing bleeding into the brain tissue and resulting in a hematoma (a blood mass) in the brain. Prompt removal of the blood mass is necessary to limit or prevent long-term brain injury.
Clear visualization and imaging of the blood mass and any surrounding surgical field facilitates removal of the blood mass. Removal and visualization can often be accomplished through a cannula and obturator assembly, placed through a hole drilled in the skull near the site of the hematoma. The site of the hematoma can be accurately identified using a CT scan.
To aid in placement of the cannula and obturator assembly precisely at the hematoma, and also to aid in inserting the cannula through a route least likely to damage healthy brain tissue, neurosurgeons use sophisticated and costly stereotactic surgery systems or neuro-navigation systems. These systems depend on previously obtained MRI or CT scans, which may be several hours old, and thus not perfectly reflective of the shape and location of the blood mass at the time of surgery. In these systems, visual confirmation that the cannula distal end is properly positioned can be accomplished only after the obturator has been removed from the cannula. If the distal end has not been accurately placed, the obturator must be re-inserted, and the cannula and obturator assembly must be manipulated, perhaps repeatedly, until, after removal of the obturator, the blood mass is visible.
A less sophisticated method, used before these expensive neuro-navigation systems and stereotactic systems became standard and still used where these systems are not available, involves large craniotomies, exploration and direct visual search for a blood mass, extensive tissue dissection, and invasive instrumentation, all associated with high mortality and morbidity.